An induction heating roller apparatus includes a hollow roller made of a metal having suitable degrees of permeability and conductivity (or electrical resistance), e.g., carbon steel, and an induction heating winding structure forming a primary coil, the structure being supported for relative rotation within the hollow roller. In turn, the roller is supported for rotation preferably by a separate bearing structure. The winding structure is in the form of a coil wound on a bobbin-like iron core coaxially within the roller, with its lead wires being led outside the roller through the shaft of the coil (sleeve rod) extending through the roller shaft. The leads are then connected to an AC power source of commercial frequency.
In the induction heating roller device described above, turning the power switch on causes an exciting current to flow through the coil, with the resulting magnetic flux circulating through a magnetic circuit where the flux pass through the coil via the bobbin-like iron core made of a core material, such as silicon steel sheets, reaching the roller side, radially moving and then turning back to pass through the cylindrical portion of the roller, reaching the opposite roller side; thus, an eddy current based on alternating magnetic flux flows through the roller body, particularly the cylindrical portion, generating Joule heat (eddy current loss).
Such induction heating roller is used to effectively transmit pressure and heat to a material to be processed in printing, embossing of sheets, calendering of paper, and the like operation.
FIG. 10 shows the common construction of such induction heating roller apparatus, comprising a roller 1 and flanges 2A and 2B fixed to the opposite ends of the roller 1 by bolts 3A and 3B to close the opposite ends. The characters 4A and 4B denote driving shafts integral with the flanges 2A and 2B, having through-holes 3A and 3B, respectively. The shafts being rotatably mounted on the machine frame by bearings, not shown.
The numeral 5 denotes an induction heating winding structure comprising a bobbin-like iron core 6 and an induction coil 7 wound thereon. The numeral 8 denotes lead wires connected to the induction coil 7 and led outside and connected to an AC power source. The characters 9A and 9B denote sleeve-like rods axially projecting from the opposite ends of the winding structure 5 to support the latter and extending through the through-holes 30A and 30B of the driving shafts 4A and 4B. Bearings and 10B are interposed between the support rods 9A, 9B and the through-holes 30A, 30B. A stop ring 11 for the bearing 10A is installed in the wall surface of the through-hole 30A, and stop rings 12 and 13 for the bearing 10B are installed in the wall surface of the through-hole 30B. Further, the lead wires 8 are inserted in the through-hole of one support rod 9B and allowed to be led outside. Thus, the support rods 9A and 9B and hence the induction heating winding structure can be stationary, while the driving shafts 4A and 4B of the roller are rotatable.
In this connection, it is to be mentioned that this type of an apparatus is sometimes used for imparting patterns to sheets, such as paper, non-woven fabrics, or iron sheets. To this end, the outer surface of the roller is embossed with a required pattern, but when it is desired to impart a different pattern to sheets, another roller having such different pattern has to be used. To this end, the roller 1 alone has to be separated for exchange from the winding structure.
Conventionally, for such exchange, the roller 1 built in the apparatus is mounted as such on a suitable stand. Then the bolt 3A for the driving shaft 4A on the left hand is removed to release the flange 2A from the connection with the roller 1, and the stop ring 11 is removed. Then the flange 2A and the driving shaft 4A are moved leftwardly of the roller 1 and thereby separated from the roller 1.
The bolt 3B for the driving shaft 4B on the right hand is removed to release the flange 2B from the connection with the roller 1, and the inner stop ring 12 is removed. Then the flange 2B and the driving shaft 4B are moved rightwardly of the roller 1 and thereby separated from the roller 1. Thereafter, the induction heating winding structure 5 is withdrawn together with the support rods 9A and 9B from the roller 1. The resulting state is shown in FIG. 11.
As a result of this operation, the roller 1 is separated from the other components and exchanged for another roller 1 and the components are assembled in the order reverse to that for disassembly.
However, since the flanges 2A and 2B are tightly fitted in the roller 1, the withdrawal of the individual flanges from the roller 1 is no easy operation according to the separating procedure described above. Further, when the bearings 10A and 10B are separated from the support rods 9A and 9B in separating the driving shafts 4A and 4B together with the bearings 10A and 10B from the support rods 9A and 9B, there is nothing left to support the support rods 9A and 9B, causing the latter to incline under gravity or fall down onto the inner surface of the roller 1; thus, care must be taken in performing this operation.
The assembling operation subsequent to the exchange of the roller 1 comprises the steps of inserting the induction heating winding structure 5 with the support rods 9A and 9B into the roller 1 and fitting the front ends of the rods 9A and 9B in the bearings 10A and 10B disposed inside the driving shafts 4A and 4B. However, the involved fitting operation is not easy and then, with this fitted state maintained, the flanges 2A and 2B have to be attached to the roller 1; thus, this operation is very troublesome.
That is, the mounting and dismounting operation of the roller and flanges of this type of apparatus are made troublesome by two factors; (1) the tight fit between the roller and the flanges, and (2) the separable construction of the three component sections: the roller, the driving shafts integral with the induction heating winding structure.